This study of twenty healthy young adults highlights the acute effects of night-time light exposure on sleep macro and micro-architecture, heart rate, and oral glucose tolerance test responses. This was a randomised trial where the group was divided into Light or Dark groups and run parallel for three days and two nights. The Light group slept on Night 1 in the dark at <3 lux, and on Night 2 slept with overhead room lights at 100 lux. The Dark group slept in the dark at <3 lux on both Nights 1 and 2. Overnight polysomnography was performed to assess Slow Wave Sleep activity (SWS), slow oscillatory (SO) activity, heart rate (HR). A two-hour oral glucose tolerance test (OGTT) was performed each morning after waking.
Results demonstrated that while there was no change in SWS activity and SO activity, there was a higher HR across the night from Night 1 to Night 2 in the Light vs the Dark groups. Initial insulin responses from Night 1 to Night 2 also showed a higher insulin response in the Light vs the Dark group.
This study demonstrates that a single overnight light exposure increases heart rate during sleep and decreases insulin sensitivity the following day. These responses suggest that night-time exposure elevates autonomic activity and impactsDaniela Grimaldi, Kathryn Reid, Ivy Mason, Chloe Warlick, Roneil Malkani, Sabra Abbott, Phyllis Zee, 012 Overnight light exposure acutely increases heart rate during sleep and decreases insulin sensitivity the following day next day metabolic responses.
Full article accessible via: https://doi.org/10.1093/sleep/zsab072.011
References:
Daniela Grimaldi, Kathryn Reid, Ivy Mason, Chloe Warlick, Roneil Malkani, Sabra Abbott, Phyllis Zee, 012 Overnight light exposure acutely increases heart rate during sleep and decreases insulin sensitivity the following day, Sleep, Volume 44, Issue Supplement_2, May 2021, Page A6, https://doi.org/10.1093/sleep/zsab072.011
